This invention pertains to the art of heat exchangers and more particularly to heat exchangers used for heating a flow of air passed in close communication therewith.
The invention is particularly applicable to a heat exchanger of the cross-over type which may be either axially or transversely mounted relative to an air flow and will be described with particular reference thereto. However, it will be appreciated by those skilled in the art that the invention has broader applications and uses.
Heat exchangers of the cross-over type employed for heating a continuous flow of air passed in close proximity thereto have been known in the art. Generally, this type of heat exchanger design includes some type of inner shell which defines a heating chamber and which is adapted to receive a burner in operative association therewith for causing combustion of a continuous fuel supply therein. Surrounding this inner shell and radially spaced therefrom is an outer shell with the space between the inner and outer shells defining an air flow passage. The outer shell includes one of various means for defining a gaseous flow passage or chamber thereover and which passage or chamber is placed in gaseous flow communication with the heating chamber through one or more cross over members or areas. This arrangement allows the products of combustion generated in the heating chamber to be conveyed therefrom by means of the cross over member or area into the gaseous flow passage or chamber and then exhausted outwardly of the heat exchanger structure. An air flow to be heated is continuously directed by fan means or the like through at least the air flow passage into close proximity with the inner and outer shells for heating and subsequent dispersement for heating a room, other enclosure or the like.
However, prior heat exchangers of this general type have had several drawbacks. First, the designs have been such that they were adapted to provide heating for an air flow passed in only a single direction relative to the heat exchanger. Typically, this direction was axially of the exchanger and air flow passage but there have been some exchanger designs adapted for transverse mounting relative to an air flow. However, no prior heat exchanger designs of this general type have been developed which would successfully facilitate alternative mounting of the heat exchanger either axially or transversely of an air flow. Thus, for different heat exchanger applications, i.e., where it was necessary or desirable for some reason to mount a heat exchanger in one direction or another relative to an air flow, different heat exchanger designs and embodiments had to be provided.
Another problem with prior heat exchanger designs of this general type has been in the conveyance of the products of combustion from the heating chamber, through the cross over member or area and then through the passage or chamber in the outer shell to an exhaust area. In view of the fact that the products of combustion are hot and provide an additional vehicle for heating an air flow, it is desirable to provide a sinuous travel path for the products of combustion along the passage or chamber in the outer shell to achieve a more efficient air flow heating arrangement. However, prior art heat exchangers have not fully capitalized on this desirable arrangement and, quite often, simply provided a simple or direct gaseous flow path to the exhaust area.
Still another problem area with prior heat exchangers of this general type has been in accommodating flow through the air flow passage around the cross over member or area itself. Because this cross over member or area is oftentimes located directly in the air flow path and conveys the very hot products of combustion from the heating chamber to the gaseous flow passage or chamber in the outer shell, a substantial heat build-up is present at the cross over area. Because of this heat build-up, it was necessary to utilize special and costly heat resistant metals or materials for constructing the cross over member in order to avoid breakdown of the heat exchanger at this area. Moreover, the cross over member comprises an impediment to smooth air flow along the air flow passage and reduces the overall heat exchanger efficiency. Thus, the amount of fuel and electrical power required to achieve a desired heat exchanger rating is higher than it might otherwise be.
The subject invention contemplates new and improved apparatus which overcomes all of the above referred to problems and which provides a new heat exchanger structure of the cross over type which is simple in design, economical to manufacture, provides increased heating efficiencies by fully utilizing the heated products of combustion, provides an improved air flow around and a heat sink at the cross over member or area and which is readily adapted to mounting either axially or transversely of an air flow to be heated.